The present invention relates generally to coupling devices, and more particularly to such devices for joining components in piping systems.
Fluid piping systems typically include components, such as valves, hydrants, tee's, elbows, etc., which are adapted to be adjoined to piping or other components. These components may include any of several types of joint connections, e.g., mechanical joint ("MJ"), flange, or push-on fittings.
Pipelines and piping systems ire subject to the effects of settling, unstable soils, expansion and contraction due to weather and other underground movement; thus, it will be appreciated by those skilled in the art that it is desirable to have a coupling assembly for connecting the components in a piping system in a manner which creates a flexible joint. To this end, there have been several attempts to design a coupling or connecting device to effect such connections.
One such device that is known in the art and referred to as an "anchor coupling" or "swivel coupling" comprises a short length of pipe with means at the ends of the pipe for enabling connection to MJ fittings. One of the drawbacks associated with the anchor coupling is that it provides joint restraint, but virtually no angular deflection when installed. Furthermore, in order to install an anchor coupling, the conduits or fittings to be connected must be in almost perfect alignment. Finally, the anchor coupling may only be used to connect MJ fittings.
Another device known in the art for use in restrained joints is a "hydrant tee" or "anchor tee", which is similar to the anchor coupling in principle and is subject to the same limitations.
Yet another device known in the art and disclosed in U.S. Pat. No. 5,335,946, issued to Dent et al. and incorporated by reference as if fully set forth herein, is a cooperating combination of a gland and a grip ring installed in restrained sealed bolted joints of fluid piping systems. The Dent et al. device comprises a cooperating combination of a metallic gland and a metallic grip ring for use in positioning, compressing and sealing a gasket about a plastic or metallic pipe. The grip ring includes two spaced apart large teeth and several spaced apart, smaller pipe-gripping circumferential teeth located between and beyond the large teeth. When the installed grip ring is restraining a pipe, the teeth penetrate the pipe to provide complete circumferential restraint.
However, one drawback associated with the grip ring device is that it must be actively engaged by the operator, i.e., the T-bolts on the gland must be tightened in order to cause the grip ring to engage. Further, the grip ring provides a poor connection to out-of-round pipe. Also, the grip ring permanently scores the surface of the pipe; therefore, the scored portion of the pipe must be cut off before the pipe may be reused. Finally, the grip ring is designed to connect fittings to pipe. Thus, a short piece of pipe must be cut and two grip ring assemblies installed--one at either end of the pipe--to connect two fittings together.
Another device found in the art is a retainer gland, such as that manufactured by Ford Meter Box Company, Inc. and sold under the trade name "Uni-Flange". The retainer gland essentially provides a friction fit and includes wedges which engage the pipe upon tightening of a bolt. As with the grip rings, the retainer gland is susceptible to interference from dirt on the pipe or the pipe-engaging surfaces of the wedges. Also like the grip rings, the retainer gland is designed to connect fittings to pipe and, thus, requires a short length of pipe with two retainer gland assemblies to connect valves, hydrants or other fittings. Further, the retainer gland provides for less angular deflection; thus, the fittings and/or pipe to be connected must be almost perfectly aligned. The retainer gland does not provide one hundred percent (100%) restraint contact. Moreover, the retainer gland requires critical torquing of the wedge bolts.
Another device found in the art for restrained connections is a flexible ball joint, such as that manufactured by EBAA Iron Sales, Inc. and sold under the trade name "Flex 900". The flexible ball joint provides fitting-to-fitting connection and is intended for use in applications in which a pipeline and components are subject to unusual movement, such as connections to a pump station or pipelines crossing unstable terrain. The ball joint allows for a minimum of fifteen degrees of angular deflection and may be used with MJ, flange and push-on fittings. One of the drawbacks associated with this device is that it offers angular deflection from a center pivot only rather than from two independent pivot points adjacent the connected fittings. This single-point deflection is not ideal for aligning fittings and/or pipes for connection. Another drawback is that this connector is not field adaptable to different types of fitting connections. Thus, a connector of this type configured for attachment to a flange fitting cannot be converted in the field to connect to an MJ fitting. Rather, the joint must be retrofitted with a new connector having ends configured for attachment to an MJ fitting.
Another device found in the art for restrained connections is a connector formed from two ball joints, such as the device sold under the trade name "Flex-Tend". This connector comprises an expansion joint with ball joints at each end. The ball joint design allows for substantial movement of pipes and/or fittings; however, pipes and/or fittings are rarely misaligned to the degree required to connect to the double ball joint configuration. Furthermore, the expansion and contraction of the expansion joint requires additional anchoring of the pipeline.
What is needed then, is a coupling assembly for connecting components of a piping system which is adaptable to different types of joint connections and which enables axial rotation and critical angular deflection of mechanical joint connections.